0°F to Celsius

-17.8°C

0°F = -17.8°C = 255.37 K

Working: (0 − 32) × 5/9 = -17.8

0 degrees Fahrenheit converts to -17.8 degrees Celsius.

To convert Fahrenheit to Celsius, subtract 32 first, then multiply by 5/9. For 0°F: 0 − 32 = -32, and -32 × 5/9 = -17.8. The subtraction comes first because the two scales have different zero points — water freezes at 0°C but at 32°F.

A quick mental estimate is to subtract 30 and halve the result, which gives about -15°C — 2.8 degrees off the exact -17.8°C. That is close enough to judge the weather, though it drifts badly at oven temperatures.

Zero Fahrenheit is not an arbitrary bottom. Fahrenheit set it at the coldest temperature he could reliably reproduce, using a brine of ice, water, and salt — which is why it lands on the untidy −17.8°C. The scale's zero encodes a piece of eighteenth-century laboratory practice rather than anything about water.

Nearby temperatures

Fahrenheit	Celsius
32°F	0°C
40°F	4.4°C
50°F	10°C
60°F	15.6°C
68°F	20°C
72°F	22.2°C
80°F	26.7°C
90°F	32.2°C

Try another value

From

°C

77°F

All scales

Celsius (°C)25 °C

Fahrenheit (°F)77 °F

Kelvin (K)298.15 K

Frequently asked questions

What is 0 degrees Fahrenheit in Celsius?

0°F is -17.8°C. Subtract 32 from 0 to get -32, then multiply by 5/9 to get -17.8.

What is the formula for Fahrenheit to Celsius?

°C = (°F − 32) × 5/9. Subtract 32 from the Fahrenheit temperature, then multiply the result by 5/9 (about 0.5556).

For any other value, use the full Temperature Converter on BrainVert.